Mental Retardation Carolyn R. Fallahi, Ph. D.

Mental Retardation & Testing • What does intelligence testing measure? – Practical problem-solving ability – Verbal ability – Social competence (Sternberg, 2000). – Binet: “Judgment, good sense, practical sense, initiative, the faculty of adapting one’s self to circumstances.” – Wechsler: “The overall capacity of an individual to understand and cope with the world around him.”

Intelligence • What is intelligence made up of?? – Spearman: general factor (g) – Gardner: multiple intelligences

• The Intelligence Quotient (IQ) – IQ = MA/CA X 100. – Wechsler: deviation IQ – how far a particular child’s score on an intelligence tests deviates from the average scores of all children of that age. – WISC-IV (Mean=100; SD=15).

Daniel Hoffman v. Board of Education • The issue of high stakes testing. • Measuring intelligence in young children is problematic. • Bayley Scales of Infant Development – II • Are IQ tests culturally biased?

Diagnosis and Assessment • Intelligence + Adaptive functioning. • Vineland Adaptive Behavior Scales • American Association on MR adaptive behavior scale

Diagnostic Criteria for MR DSM Code #

Severity

IQ Scores

317

Mild Mental Retardation

50-55 to 70

318.0

Moderate Mental Retardation

35-40 to 50-55

318.1

Severe Mental Retardation

20-25 to 35-40

318.2

Profound Mental Retardation

Below 20 or 25

319

Mental Retardation, Severity Unspecified

Cannot obtain IQ score

Cognitive Abilities • • • • •

MR = significant cognitive problems. Mild MR versus moderate and severe MR. Self-image? Peer relationships. Health problems.

Comorbid disorders • 30-70% experience a comorbid disorder • depression • Anxiety

Prevalence • • • • • •

1.8% and 2% prevalence rates 85% of people with MR have mild MR Moderate = 10% 3-4% severe MR 1-2% profound MR More boys than girls are diagnosed with MR. • Higher percentage of Afr Ams than Eur Am children are diagnosed with MR. Why?

Families of children with MR • Family issues • Parents • Siblings

Etiology • MR due to organic cause. – identifiable biologically based problems – including chromosomal and genetic malformations – toxins from the environment – nutritional deficits – diseases that afflict pregnant women, infants, and children.

Chromosome abnormalities • Down syndrome is the most common chromosomal cause of MR. It is usually caused by a “nondysjunction of the 21st chromosome from the mother. That is, the mother’s 21st pair of chromosomes fails to separate during meiosis (cell division). When this undivided pair is combined with the father’s 21st chromosome, the child receives 3 copies of the 21st chromsome (thus the label trisomy 21). • In rare cases, Down syndrome is caused by the translocation of part of chromosome 21 onto chromosome 14.” (Haugaard, 2008)

Symptoms of Down Syndrome • Smaller brain size • Normal development through 1st year, then decline. • Mild to severe range of MR • Problems with expressive language • Problems with verbal short-term memory • Socially oriented

Genetic Causes of MR • Fragile X Syndrome: is the most common cause of an inherited MR. It is found in about 1 of 4,000 births in males and 1 in 8,000 births in females. • Fragile X syndrome is caused by a mutation on the long arm of the X chromosome. The severity of the disorder depends on how fully mutated the gene is. • Cognitive impairments in boys versus girls. • Problems with expressive language. • High levels of social anxiety.

Phenylketonuria (PkU) • PKU is a disorder that results from a mutation of the Phenylalanine hydroxylase (PAH) gene, which is found on the short arm of chromosome 12. • Prevalence: 1 in 10,000 births. • Problems metabolizing phenylalanine

Williams Syndrome • Williams syndrome is a disorder caused by genetic deletions on the 7th chromosome. • Prevalence: 1 in 7,500 births. • IQ problems; some significant cognitive deficits.

Prader-Willi Syndrome • Prader-Willi syndrome is caused by abnormalities on the 15th chromosome. • “In about 65% of cases, this abnormality is due to several gene deletions from the paternal chromosome; in most remaining cases, it is due to a person receiving both copies of chromosome 15 from the mother.” (Haugaard, 2008

Environmental Toxins • Several environmental toxins can cause MR. – high doses, toxins = severe or profound MR. – Smaller doses – may have a negative, but less noticeable influence on the child (such as a loss of IQ points). – Lead poisoning. – Fetal alcohol syndrome and effects. – Mercury exposure. – Nutritional deficits. – Infectious diseases.

Early Intervention • Preschool years, B to 5 years. • This has been mandated since 1986 (federal law). Those with an identified disability must have access to services beginning at 3. • Focus: cognitive skills, social skills, and self-care. The programs also provide cognitive stimulation, help children develop gross and fine motor skills, and teaching school readiness.